71C/72C rebuild specs: clearances and snap rings

Everything below is scoped to the cast-iron 71C (1017) and 72C (1018) in-line clutch packs, since that's what the parts diagram and the factory clearance tables cover. The 1004/1005 V-drive shares the same clutch-pack numbers.

Clutch clearances

The V-drive manual gives the same clearances for the V-drives: a 1004 uses the 71C figure and a 1005 uses the 72C figures.

Plate counts

Forward pack: a 71C uses 4 steel plates and 5 friction plates. A 72C uses 6 steel and 7 friction. The reverse clutch pressure plate is common to both series and rides on 11 return springs, part number 71-97.

Older bushing-style direct drives (built before around September 1978) used a single reverse plate, which was fine behind a smaller engine like a 302 or 305. Current units use two reverse plates. Chris's read is that the second plate was added for bigger engines like a 350 or 351.

Inside the pack, the 71 series uses two snap rings and the 72 series uses three. There's a groove on top of the pressure plate that looks like it's cut for a snap ring. It isn't; it does nothing.

71 vs 72 clutch pack teardown

On the factory parts diagram these are the reverse clutch pressure plate (item 54), its pressure plate springs (item 57), and the forward pack's steel plates (item 72) and friction plates (item 73).

Snap-ring sizes and colors

The forward-pack snap ring at position 75 comes in more than one thickness depending on how the pack stacks up, and the factory tells them apart by color:

If someone's stretched a snap ring getting the pack apart and reused it, that's a tell that someone's been inside the transmission before you.

Springs

Table 5 of the factory manual lists four springs:

Reduction preload

Current-production reduction units set bearing preload with a solid spacer: rolling torque 5 to 30 in-lb before you bolt the reduction unit to the transmission, giving 0 to 0.005 in of end play. Solid spacers come in 11 lengths, .820 to .857 in, and the bearing cup and cone are a matched pair. On a 1.91:1 reduction specifically, the six pinion-carrier lock bolts torque to only 5 ft-lb with the lockplate tabs bent against the flats, which is well below the rest of the case's bolt torques. Full bolt-by-bolt numbers are on the torque specs page.

Kits that cover each part

No single kit covers a full rebuild; the factory splits seals from clutch parts:

• A4867HA ($303.75): 71-72 Series Gasket & Seal Kit, oil seals and sealing rings, and includes the service gasket kit. No clutch parts.
• A4867AE ($318.75) (71C) / A4867AB ($312.50) (72C): forward clutch pack kits, pressure plates, steels and friction plates. No seals. These complement the HA kit rather than replace it.

See which rebuild kit you need for the full breakdown across 71/72, 5000 and ZF.

Related reading

• Velvet Drive torque specs
• Paper vs. bronze clutches
• Snap rings installed wrong
• How we rebuild a marine transmission

Not sure which parts you need? Call (804) 333-3677, Monday through Friday 9 to 3 Eastern, or email sales@halemarine.com.